Manufacture or treatment of armor-plates.



No. 690,96l. Patented Jan. l4, I902.

B. K. JAMISON.

MANUFACTURE UR TREATMENT OF ABMOR PLATES.

(Application filed Dec. 24, 1897.) I (No Model.) 2 Sheets-$heei I.

N0. 690,96I. Patented Ian. 14, l9fll2. B. K. JAMISUN.

MANUFACTURE 0R TREATMENT OF ARMOR PLATES.

(Application'filed Dec. 24, 1897.) (No Model.) 2 Sheets-shew 2.

WITNESSES 2 INVE NTOR $94 M i 4W,

By his Azzarnej's.

we NORRIS PETERS 00., momdma. WASHINGTON, 0.1;.

lUNrrnn Sterne BENTON KNOTT JAMISON, OF PHILADELPHIA,

BY MESNE ASSIGNMENTS, TO NAT IONAL STEEL PENNSYLVANIA, ASSIGNOR, REFINING COMPANY, OF

WILMINGTON, DELAWVARE, A CORPORATION OF DELAW'ARE.

MANUFACTURE OR TREATMENT OF ARMOR-PLATES.

SPECIFICATION forming part of Letters Patent No. 690,961, dated January 14, 1902.

Application filed December 24, 1897. Serial No. 668,284.

To ctZZ whom it may concern.-

Be it known that LBENTON KNOTT JAMISON', of Philadelphia, in the State of Pennsylvania, but now temporarily residing in London, England, have invented certain new and useful Improvements in the Manufacture or Treatment of Armor-Plates and in Apparatus Employed Therein, of which the following is a specification.

This invention has reference to the manufacture or treatment of armor-plates, and more particularly of armor-plates of low-grade or mild open-hearth steel containing, say, from .20 to .50 per cent. of carbon and alloyed or not with a small percentagesay from one and one-half to five per cent-of nickel.

The invention chiefiy consists of an improved and economical method of hardening the face of the plates to any required depth, so as to increase their resisting power and at the same time render them more tenacious and less liable to fracture, and then toughening the face of such hardened portion.

According to my invention I take a steel plate which is preferably of low-grade or mild open-hearth steel and heat it slowly and gradually until it attains a brightred heat and then with as little delay as practicable immerse it to a depth corresponding with the depth to which it is required to harden it in a cold bath of hardening liquid, such as is hereinafter described, of such character that the contact of the heated metal and liquid bath will generate hydrocarbon gases, which will be absorbed or taken up by the metal. The time occu pied in slowly heating the plate to a bright red, as above described, will depend upon the thickness of the plate. For a plate six inches thick the time will be from three to four 0 hours. I leave the plate in this bath for a sutficient length of time to effect the hardenin g processnamely, until hydrocarbon gases cease to be generated from the bath and to be absorbed by the plate-the time depending upon the depth to which the hardening is to extend-say thirty to forty minutes for a depth of three inchesand I maintain the bath as nearly as practicable at a uniform temperature during the whole time, so that the chemical properties of the liquid will be (No specimens) retained and the plate be gradually cooled. This temperature should be about the normal temperature of watersay to Fahrenheit-for low-carbon steels-that is, steels containing not more than .50 per cent. of carbon. For higher carbon steels containing more than .50 per cent. carbon the temperature of the bath should be raised to about Fahrenheit before the plate is put in and be kept at that temperature. The maintenance 60 of a practically uniform temperature may be best effected by admitting more cold hardening liquid through a regulated inlet to the lower part of the bath, providing the bath at the same time with one or more overflow-ori- 65 fices, so that the level of the liquidin the bath,

and therefore the depth of immersion of the plate, shall be kept uniform.

The effect of the above treatment is that the portion of the plate which is immersed in 70 the hardening liquid undergoes a molecular change from a granular to a fibrous condition, blending with the softer or untreated back portion of the plate, but leaving this backing or untreated portion in its original condition.

While the desired portion of the plate is being treated and hardened, as above described, I preferably place upon the non-submerged part or back of the plate a hot plate or several hot plates in succession, according to the thickness of the plate under treatment.

The hot plate or plates should be heated to a greater heat than the plate under treatment, preferably to a bright-red heat, which is a greater heat than that of the plate under treatment at the time the hot plate or plates are applied thereto, the said plate under treatment being then at a black heat. This have the effect of drawing a portion of the 0 carbon from the back part of the plate and of annealing this portion, thereby rendering it exceedingly tenacious and ductile and counteracting the tendency of the front portion of the plate to crack when it receives the im- 5 pact of a heavy projectile. I have found that in dealing with an armor-plate of six-inch thickness a good result is obtained by applying the first hot plate about four minutes after the armor-plate has been put in the bath, I00

leaving it for about eleven minutes, then applying another hot plate and leaving this about sixteen minutes.

For the purpose of obtaining a plate of three different grades of steel the face of the front or hardened portion of the plate may be subsequently toughened by surface tempering in any suitable manner, as by raising to a suitable temperature and quickly cooling. For example, the surface to be toughened may be brought to a temperature of from 230 to 300 centigrade in a furnace or by dipping into a'bath of fusible metal or oil heated up to the requisite temperature, and then suddenly plunged into water at ordinary temperaturessay 16 to 20 centigrade. In this case I obtain a plate of three grades of steel, differing in their physical condition, but not in their chemical composition-namely, the surface which has been toughened by reheating to a low temperature and sudden cooling, the portion hardened by the action of the hardening-bath, and the remainder eitherin its original untreated condition or more or less annealed by the application of a hot plate or hot plates to the back, as above described. I use the word tempering in its ordinary sense, as understood by those skilled in the artto mean mitigating, partly removing, moderating the effects of previous hardening. The result of this step in the present case is a toughening, depending in degree on the temperature employed, and a considerable gain in tensile strength, which increases the ability of the plate to resist the impact of shot.

While any suitable bath liquid may be util ized for the treatment of plates in accordance with my invention, I prefer that the bath liquid shall be composed of the following ingredients in the proportions named: sweet spirits of niter, (B. P.,) three ounces; aqua-ammonia, (specific gravity .88,) three ounces; chlorid of ammonium, six ounces; sulfateof zinc, threeounces; ground alum,(best commercial,) (Al 3SO .Am SO .24161 0,) three ounces; glycerin, eight ounces; water, one gallon.

A liquid composed of the same ingredients has already been proposed for hardening and refining steel; bu t'the proportions have been different-that is to say, the proportions of chlorid of ammonium and of glycerin have been considerablyless-and I have found by experiment that a good result is not attained unless the proportions of these two ingredients are as large as above given.

The order in which the ingredients of my hardening liquid are mixed and the time allowed to elapse between the additions of the several ingredients areim portant. I firstintroduce into the water the ground alum and the sulfate of zinc, and I allow the mixture to stand for about twelve hours or longer. I then add the glycerin and afterward as soon as practicable the other ingredients. When all the ingredients have been added and thoroughly mixed, it is desirable to allow the mixture to stand for about twenty-four hours be fore use.

I may use merely a mixture of glycerin and water in the proportions of eight ounces of glycerin and one. gallon of water; but while this last-named bath answers Well and is found to be entirely practical it has also been found by experiment that the first-named ingredients and proportions are better adapted for the purpose.

It should be stated that either of the baths above described gives good results in the treatment of armor-plates of low-grade steel, and in practice this process (which should be understood as being distinguished from the process of tempering steel in oil) changes the nature, the physical structure, and molecular construction of the steel, whereas the tempering of steel in oil simply tempers the steel more slowly than is done by tempering in water and other agents, leaving the steel less hard, but somewhat tougher than water-tempered material, and, further, the changes caused bythe oil-tempering process are merely temporary and do not change the physical and granular structure of the metal, and such changes of the metal caused thereby can be readily neutralized by reheating and allowing the metal to cool.

The plates treated according to my invention, as above described, can be reheated, forged, and reforged Without changing their nature, physical structure, or molecular construction.

The treatment of a plate when at proper temperature by this liquid causes that portion thereof which is subjected to the bath to absorb a large quantity of hydrocarbon gas, which has a strong affinity for the metal when the latter is in a heated state, thus facilitating this absorption, which has been shown to greatly improve the quality of the steel in its tensile strength and elasticity, and yet not deteriorate it in its capacity or ductility.

By many tests this process has been found to be especially adapted for the treatment of armor-plates, since when such a plate is composed entirely of low-grade nickel-steel it may be converted to a high-grade steel through a certain portion thereof, while the remainderis left in its original condition, and when the portion which is treated consists ofa face of the plate and the treatment is permitted to extend to a considerable distance below the surface thereof a plate will be produced the face of which will have a greater resisting power than the highest-grade nickel-steel when untreated, while the back being lowgrade nickel-steel will prevent the cracking or shivering of the plate, as is well known in composite armor-plates. To produce such a plate by my improvement, it is only necessary to form it from low-grade or mild openhearth steel, with, say, from .20 to .50 per cent. carbon and an alloy of from one and one-half to five per cent. of nickel, bringing the same to the required temperature for the proper "treatment of the plate and immersing a portion thereof in the bath above described to the depth required to face-harden the same in the manner hereinbefore set forth.

Although I have mentioned that the percentage of nickel may be from one and onehalf to five, my experiments have shown the best results when the percentage of nickel has been three and one-fourth. If no nickel be employed, the percentage of carbon should be .55 to .65. I may also employ with or without nickel a proportion of manganesesay .60 to .75 per cent.and the metal should contain as little silicon, sulfur, and phosphorus as practicable.

I will now describe one form of apparatus for carrying out the mode of hardening in the hardening-bath, as above described.

In the accompanying drawings, Figure l is an elevation, partly in section, of one modification of apparatus. Fig. 1 is a vertical section on the line 1 of Fig.1 and showing the hot plate X in position. Fig. 2 is an elevation, partly in section, illustrating another modification.

Referring first to Figs. 1 and 1, A'represents a furnace for heating the plates. As close to the furnace as practicable is a bathtank D, to and from which the plates may be conveyed by a traveling crane B, mounted on rails O. In the bath-tank there is a grating-like support (or supports) Ewith feet E for an armor-plate,(shown at F,) and this tank has leading therefrom an overflow-pipe G,in which is a valve H for regulating the level of the liquid within the tank, as will be readily understood, a hand-wheel I being connected with the valve to operate the same, and for convenience in determining the level of the liquid within the bath-tank a graduated scale J may be provided. The outer end of the pipe Gr empties into an overflow tank or reservoir K, and this tank is preferably of a size to act as a reservoir to store a sufficient quantity of bath liquid for a continuous operation. A pump L is connected by a pipe M with the overflow-tank K, the object of which pump is to force the bath liquid through a pipe N to a cooling-coil O, which latter is arranged within a casing P, having a spray-nozzle Q at the upper portion thereof, which is fed by suitable water-supply, so as to reduce the temperature of this coil and the liquid passing therethrough, and the water which accumulates within the casing is drawn therefrom through the waste-pipe R, or the casing may be filled with ice. From the coil 0 leads a pipe S to a flush-tank T, the latter being of sufficient capacity to hold enough of the bath liquid to supply the hath-tank D with sufficient speed to maintain the temperature within the batlrtank when a hot plate Fhas been placed therein, and for the regulation of the downflow of the liquid from the flush-tank a valve U is interposed in the pipe V, which leads from the flush-tank to tho bath-tank.

The operation of this apparatus is as follows: The pump L being set in operation, a portion of the liquid will be drawn from the reservoir and overflow-tank K and forced upward through the coil 0, where this temperature will be reduced, and from thence it will be conveyed to the flush-tank T, where it is stored for use when needed. Now when a plate to be treated has been properly heated within the furnace A it is conveyed therefrom by the traveling crane B to the bathtank D, deposited upon the supportlE within said tank, and immersed to the depth that it is desired to harden the surface of said plate,

' and the proper flow of bath liquid to the bathtank will be established by the manipulation of the valve U, and the level of this liquid Will be maintained at the desired point by the adjustment of the valve H.

When the plate is first introduced into the bath-tank, it is obvious that the intense heat thereof will tend to greatlyincrease the temperature of the bath; but as it is essential that the temperature of this bath should not be unduly increased, as the chemical action thereof would be altered, the supply-valve U is so manipulated at this stage of the process as to greatly increase the flow of the bath liquid to the tank; but this increased flow will not alter the level of the liquid within the tank, since the overflow is of a capacity sufficient to carry away this increased supply; but the result of this increased supply will be to maintain the temperature of the bath liquid within the tank at the proper degree, which may be determined by a thermometer W, extending downward below the level of the bath.

In mild or small classes of work it may be found desirable to maintain the overflow or level of the bath liquid at a given point and regulate the depth of the plate therein by the movement of the supports. This may be accomplished by the modified construction shown in Fig. 2-that is to say, by providing the support a with suitable guideways within the bath-tank b and supporting it upon a piston-rod c, which passes through the bottom of the tank and into a hydraulic cylinder d, where it is attached to a suitable piston, inlet and outlet pipes e 6 being arranged for the operation of the piston. Thus the depth of the plate within the bath may be regulated by the lowering and raising of the support. When plates with curved faces are to be treated, the upper surface of the supports within the bath-tank may have a similar curvature therein, so that said plates may be placed firmly against the supports, thereby preventing a tendency to warping.

X, Fig. 1 represents a hot plate placed upon the non-submerged plate F for the purpose hereinbefore described.

I make no claim herein for the novel solution herein set forth nor for the method of preparing such solution, as these features of my invention form the subject-matter of a divisional application filed by me, Serial No. 20,565, dated June 16, 1900.

. What I claim, and desire to secure by Letters Patent, is-

1. The described treatment of armor-plates, which consists in slowly heating a steel plate to a bright-red heat, submerging it when at this heat in a bath of hardening liquid to a depth corresponding with the depth to which it is required to harden the plate, keeping it in the bath for a sufficient length of time to efiect the hardening process and maintaining the bath during the process as nearly as practicable at a temperature of about 60 to 70 Fahrenheit whereby the face of said plate is hardened to the required depth, and then toughening the face of the hardened portion in surfacetempering, whereby an armorplate of three different grades of steel may be obtained, substantially as set forth.

2. The mode of manufacturing an armorfaced plate hardened to any required depth, which consists in slowly heating a plate of low-grade or mild open-hearth steel containing from .20 to .50 per cent. of carbon, and alloyed with from one and one-half to five per cent. of nickel, to a bright-red heat, submerging it when at this heat for a sufficient length of time to efiect the hardening process in a 30 bath of hardening liquid to a depth corresponding with the depth to which it is required to harden it, maintaining the bath during the process at as nearly as practicable a temperature of about 60 to 70 Fahrenheit 5 by cooling it,fannealing the back portion of the plate by placing upon the back of the plate when so heated, a plate heated to a greater heat, as a white heat, removing the plate from such bath, and then toughening 40 the face of the hardened portion of the plate by surface-tempering, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence of two subscribing 45 

